The Apicomplexa comprise a phylum with about 4,500 named species, all parasitic, of the kingdom Protozoa. Its principal groups are gregarines, hemogregarines, coccidia, hemsporina (malaria parasites and their relatives) and piroplasms. A classification of the Apicomplexa has been completed to suborder by the Principal Investigator. It is proposed, in this second year of the project, to complete the classification to genus, giving a diagnosis of each taxon. In addition, the nomenclature of the phylum will continue to be reviewed and revised as needed, new species of apicomplexan protozoa will be searched for and described, and, if possible, the life cycles of selected species will be worked out.